Force interaction in low-amplitude ac-mode atomic force microscopy: cantilever simulations and comparison with data from Si(111)7x7

Numerical simulations of cantilever resonance spectra are presented using a model for the tip-surface interaction including a long-range van der Waals force, an interatomic force described by a Morse function, and the treatment of surface elasticity as a linear spring. Simulated resonance spectra are compared with experimental data obtained from the interaction between an oscillating tungsten tip and a Si(111)7 x 7 surface at different tip-to-surface separations. The simulations show that the tip probes only the attractive part of the interaction force, and that interatomic binding energy variations on the order of 1 eV can be resolved without including energy dissipation at the surface in the model.